Various apparatuses have been suggested over the years for travelling on difficult terrains. Of these, several are compact apparatuses allowing one person, such as a person on skis, to be pushed or pulled using a track rotatably driven by a motor. Examples can be found in documents FR-2,431,304 (Jaulmes) published on 15 Feb. 1980 and in U.S. Pat. No. 4,519,470 (Allisio) published on 28 May 1985. Numerous other examples exist. Most of these apparatuses use a gasoline engine to rotatably drive the track. Some use an electric motor. Apparatuses of this sort can be useful as light means of transportation, especially where it is difficult or even forbidden to travel using a larger vehicle. For example, in terrains with a snow-covered surface, the snow could be too powdery or too deep to use a snowmobile. Another advantage of such apparatuses is that it is much simpler and easier to transport them in another vehicle than is the case with a larger and heavier vehicle, for instance a snowmobile.
Unfortunately, none of these previously-suggested apparatuses has proven fully adapted to the very rigorous winter conditions encountered during parts of the year in places where such apparatuses are likely to be useful. For instance, a very cold temperature can significantly hinder the reliability and the autonomy of an apparatus having an electric motor powered using batteries. In the case of a gasoline engine, the combination of cold weather and heat released from the engine can cause ice and compacted snow to build up at sensitive points of the apparatus. Moreover, milder temperatures are more likely to cause water infiltrations into the apparatus, which can then result in failures difficult to repair, especially if they occur deep into the forest or in other places that are difficult to access.
Also, the previously-suggested apparatuses do not allow an electric generator and/or a payload to be easily transported to places that are difficult to access, for instance places where space is limited, on rough terrains and/or on very soft terrains.
PCT patent application No. PCT/CA2011/050202, published on 20 Oct. 2011 under number WO 2011/127607, presents significant improvements in the related technical field. This patent application is from the same inventor as the present application. WO 2011/127607 discloses, among other things, various embodiments of a compact pulling apparatus that can easily travel on difficult terrains, such as terrains covered with snow, sand, mud, etc. This apparatus opens the way to many other improvements in the transport sector in general. Several solutions to problems and to specific needs in this general area have been suggested, such as having an improved drive unit can be used in many implementations.